Physiological experiments on plant roots exposed to cadmium were conducted on carrot and radish using a liquid culture and a pot experiment with a series of cadmium applications. Activities of four enzymes (catalase, peroxidase, polyphenol oxidase, superoxide dismutase), and concentrations of free proline and malonaldehyde in the roots of both plants were investigated. Results showed that the germination rate and growth of roots of both plants were inhibited at the concentration of 20mg Cd/l, and the inhibition was increased with the increasing concentrations of cadmium, both in the liquid culture and in the pot experiment; activities of the four enzymes declined similarly in both species. The concentration of proline in roots reached the maximum when the application of cadmium was at the level of 20mg/l in the liquid culture (or 20mg/kg in soil), and then it declined slowly with the increasing concentration of cadmium. However, the reverse trend was observed for the concentration of malonaldehyde. All of bio-indicators measured here was quite sensitive to the addition of cadmium.

Phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application was evaluated by pakchoi (Brassica chinensis L.) germination tests and pot experiments. Germination rates of pakchoi in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls, while the germination rate between the sedimentapplied soils was no significant difference. In pot experiments, plant height and biomass were increased by the dredged sediment application rate in the rate of lower than 540t ha 1, but decreased when the application rate was over this rate. Concentrations of Zn and Cu in pakchoi were linearly increased with the increasing of the application rate of the dredged sediment. Both plant height and biomass of pakchoi in sediment-treated red soil were higher than that in sediment-treated paddy soil, regardless the application rate. The results suggest that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment. It also showed that red soil is more suitable to accept the dredged sediment than paddy soil, and 270 t ha 1 is a safe application rate both in red soil and paddy soil.

Titanium dioxide/bentonite clay nanocomposite prepared by acid-catalyzed sol-gel method was used as photocatalyst in the reaction of cationic azo dye decomposition in water. The incorporation of TiO2 was confirmed by powder X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS). The photocatalytic activity of those nanocomposite photocatalysts was much higher than that of the pure titanium dioxides. The nanocomposite created a kinetic synergy effect in Cationic Red GTL (GTL) disappearance with an increase of the rate constant by a factor of 2.57 for neat TiO2 (P-25). The photo-activities were greatly dependent on the solution pH, and it was more effective for GTL to be degraded under alkaline condition. That was likely to contribute for the acid-base equilibria on the surface of the nanocomposite. Results also indicated that the proper addition of hydrogen peroxide could improve the decolorization rate, but the excess hydrogen peroxide could quench the formation of •OH.

A novel tri-primer polymerase chain reaction method (TP-PCR) was developed for the construction of a fused fpg gene, in which no endonuclease and ligase were used. Instead, two templates and three specifically designed primers were applied. Results showed that pheB and gfp genes, which encodes the catechol 2, 3-dioxygenase and the green fluorescent protein (GFP), respectively, were successfully fused into an fpg gene through the rapid TP-PCR system, indicating that TP-PCR method could be a useful tool for DNA fragment fusion in which no proper endonuclease sites were available.

Tissue concentrations of some mineral elements appeared to be influenced by plant Fe status. The influence of Fe deficiency on Cu uptake and accumulation in Commelina communis, and the relationship between Cu uptake and root Fe (Ⅲ) chelate reductase (FCR) activity were investigated in this study. The results showed that Cu accumulation in C. communis was increased with the drop of Fe concentration in nutrient solution. Cu uptake in C. communis was significantly enhanced by Fe deficiency. Cu uptake in Fe-deficient plants were still higher than that of Fe-sufficient plants when P-type ATPase inhibitor Na3VO4 was added in the solution, which demonstrated that Fe deficiency induced stimulation of the plasma membrane H+-ATPase did not play a role in the enhanced Cu uptake. Fe and Cu deficiency could induced root Fe (Ⅲ) chelate reductase activity in C. communis. Both Fe (Ⅲ) chelate reductase activity aud Cu concentration in roots inhibited distinctly by cycloheximide, a kind of protein synthesis inhibitor. In the time course of Fe deficiency, there simultaneously appeared Cu concentration and FCR activity peaks in roots at day 9. All above evidences demonstrated Cu uptake aud accumulation in C. communis were probably related to the root FCR activity.